Discontinuous abrasive particle releasing surfaces

ABSTRACT

Discontinuous abrasive particle releasing surfaces are disclosed that may be employed in low speed wet grinding, sanding, and polishing operations. The discontinuous abrasive surfaces of the present invention may consist of abrasive containing protrusions attached to rigid or flexible surfaces or alternatively may be comprised of closed cell foam compositions impregnated with abrasive materials such as aluminum oxide. The voids present in the discontinuous abrasive surfaces of the present invention serve to hold water and remove debris. The resulting discontinuous abrasive particle releasing surfaces are long lasting and may be made low in cost.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims benefit of the provisionalapplication filed on Feb. 1, 2006 having application No. 60/764,110 andthe provisional application filed on Jul. 5, 2006 having application No.60/818,571.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to abrasive materials and surfaces. Moreparticularly this invention relates to discontinuous abrasive surfacesemploying discrete areas containing abrasive particles that arecontinuously released in free form during wet low speed sanding,grinding, and polishing operations. The discontinuous abrasive surfacesof the present invention may consist of abrasive containing protrusionsattached to rigid or flexible surfaces or alternatively may be comprisedof closed cell foam compositions impregnated with abrasive materialssuch as aluminum oxide. The voids present in the discontinuous abrasivesurfaces of the present invention serve to hold water and remove debris.

2. Description of the Related Art

There are numerous methods that may be employed to sand surfaces. One ofthe more common methods employs sand paper. Sand paper is a thin sheetmaterial usually made of paper that has an abrasive material securelybonded onto one side. Despite its name, the abrasive is rarely if eversand. Commonly used abrasives such as aluminum oxide and silicon carbideare significantly harder than sand and are therefore more effective.This may be especially true when sanding hard materials such as glass orsteel.

Sand paper may be used by hand. This process is often referred to ashand sanding. The process of hand sanding involves using manual labor torepeatedly slide the sand paper back and forth and/or in a circularmotion over the surface until smooth. Numerous textures of abrasives areavailable. Often sanding starts out with a relatively course grade ofsand paper of about 80 grit followed by finer grades of several hundredgrit to finish the job.

One drawback often associated with sand paper is the production of dust.Sanding surfaces often produces dust that clogs the sand paper and maycreate an inhalation hazard as well. This is especially true for sandinghazardous materials such as lead paint. One way to alleviate thisproblem is by using wet or dry Emery cloth. Wet or dry Emery cloth is anabrasive coated cloth having a wide variety of grades. It is designedfor use with water thereby reducing clogging effects and significantlyor even completely eliminating the production of air bourn dust.

Another drawback with using sand paper is the tendency for the abrasiveto become dull and fall off from the sand paper backing surface.

Sanding by hand using sand paper is not always practical owing to theamount of labor required. This is especially true for large jobs thatmay take a long time resulting in fatigue.

In order to alleviate the worker fatigue issue in hand sandingoperations, numerous power sanding techniques and/or equipment have beendeveloped. Drum sanding, belt sanding, disc sanding, and orbital sandingare commonplace. These standard power sanding tools often employ someform of sand paper and therefore often suffer from many of thepreviously mentioned drawbacks. In particular is the need to change thesanding surface at regular intervals.

Numerous modifications to ordinary sand paper have been made in order toimprove the overall process. For example, sand paper having a loweredsurface density of abrasive particles is available. This particular sandpaper is made by 3M Corporation of ST. Paul Minn. and is designed foruse in sanding relatively soft materials that quickly gum up ordinarysand paper. Significant improvements in sand paper life may be realizedby reducing the tendency of particulate matter to clog the needed spacesbetween adjacent abrasive particles.

Another improvement that may be made to ordinary sand paper involves theuse of flexible and conformable foam backing. Such backing materialsallow the sand paper to conform to surface contours thereby more rapidlysmoothing contoured surfaces. Individual pieces of sand paper may beapplied to foam pads or conversely, foam pads having previously attachedsand paper may be employed. For example, Finishing Buddies (Mona LisaProducts 10770 Moss Ridge Road Houston, Tex., 77043) is a completesanding tool kit consisting of a steel wool pad, oval sanding disc, andcoarse, medium, and fine sanding pads. The oval pad is relatively rigid,and the three other sanding pads have a softer foam backing that has agreater degree of flexibility. This sanding kit is designed for slowhand sanding and finishing operations.

There are numerous flexible sanding surfaces, components, and articlescomprised of abrasive materials fixedly attached to flexible foambackings. Of particular interest is a sanding system employing arelatively thin rigid foam backing disclosed in U.S. Pat. No. 6,923,840and assigned to 3M Innovative Properties Company, St. Paul Minn. (US).U.S. Pat. No. 6,923,840 discloses a flexible abrasive product comprisedof an open cell foam backing, a foraminous barrier coating, and a shapedforaminous abrasive coating. The top abrasive coating is discontinuousand allows for holding lubricants such as water as well as spaces forremoval of debris.

U.S. Pat. No. 6,949,128 also assigned to 3M, discloses a method formaking a foam backed abrasive article having embossed raised areas.

U.S. Pat. No. 3,401,490 discloses a method for forming an abrasivearticle having a resiliently yielding open cell meltable base which ispassed under a heated roll to melt the surface to a desired depthfollowed by application of abrasive particles to the melted surface. Theresult is a flexible foam based abrasive article capable of followingirregular, uneven, or sunken surfaces.

U.S. Pat. No. 6,997,794 by James Matthew Pontieri discloses a disposablesanding device fabricated as a continuous rope like article adapted forselective segmentation. This device may employ a foam central portionalong with an abrasive outer portion. In particular the flexiblecylindrical geometry illustrated in several embodiments of the inventionlends itself to the hand sanding of difficult to reach contours and mayprove especially useful in woodworking applications.

There are numerous flexible foam based cleansing and scouring padshaving added abrasive materials. An example of this can be found in U.S.Pat. No. 3,377,151. U.S. Pat. No. 3,377,151 discloses a method formaking flexible resilient cleansing and scouring pads having an abrasivesurface. A thermoplastic foam web material is hot laminated to abrasiveweb material. In addition, one or more cleansing materials may be added.

U.S. Pat. No. 3,619,843 discloses sponges having dry impregnatedmaterials. In this invention, impregnated sponges are prepared by aprocess that deposits particulate material on one surface of the spongeand subsequently pierces the sponge with spikes to form crevicesfollowed by drawing particulate material into the crevices. The resultis a modified sponge suitable for surgical and sanitizing applications.

Also of interest are flexible open cell foam scouring and cleaning padshaving numerous protrusions. These pads are disclosed in U.S. Pat. No.4,055,029 by Heinz Kalbow, Lichgasse. The flexible pad has numerousprotrusions on the working surface having an abrasive layer. U.S. Pat.No. 4,111,666 also by Heinz Kalbow discloses a method of manufacturingflexible abrasive cleaning pads along with improvements in tearresistance.

U.S. Pat. No. 4,421,526 discloses polyurethane foam cleaning padscomposed of a densified flexible sponge like polyurethane foam materialimpregnated with various cleansing additives. Excessive mixing of thefreshly blended polymers inhibits foam formation long enough to add thecleansing ingredients. The resulting pads have added strength due tocollapsed, ruptured, and distorted cells along with fibers that resultfrom the specific mixing process employed. The result is an unusuallystrong dense flexible cleaning pad capable of absorbing substantialamounts of water that releases additives along with absorbed water ongentle squeezing.

U.S. Pat. No. 4,594,362 discloses a dry type textile cleaning articlecomprised of a friable hydrophilic polyurethane foam with incorporatedabrasive particles as well as other additives. The abrasive particlesare chemically bonded to the foam using silane coupling agents therebyreducing their tendency to separate from the mass and subsequentlydamage cloth material.

While the above described examples of foam based abrasive articlesprovide a wide variety of uses, there exists a need in the art forlightweight semi-rigid or rigid closed cell foam abrasive articlessuitable for hand and/or low speed wet sanding, and/or wet grinding,and/or wet polishing operations.

Many of the above described examples outline the use of foam withabrasive materials in order to achieve certain advantageous anddesirable properties. Still others outline some of the more simplemethods and materials commonly employed in sanding, grinding, andpolishing operations. While generally effective for sanding, grinding,and polishing, there exists a need in the industry for furtherimprovements in low speed wet sanding, grinding, and polishingoperations. For example, lapping is a process that uses specialequipment to grind surfaces to a high degree of flatness. Unfortunately,this equipment tends to be expensive and bulky. In addition, producing agood flat grind may require certain acquired skills to master. Thisresults in difficulties for small shops and individuals in the hobbyfield in grinding surfaces flat.

Another example where further improvements in low speed wet sanding,grinding, and polishing operations may be realized is in the area ofsanding cloths. Flexible abrasive cloth materials such as emery rapidlybecome dull and shed abrasive particles. Because of this, sandingoperations often require several pieces of emery cloth to complete.While making discrete zones of attached adhesive may serve to reduce thetendency of debris to build up in the sanding surface, the issue ofrapid dulling and shedding of surface abrasive particles still remains amajor issue to be resolved.

Finally, flexible abrasive surfaces employing foam have certain addedbenefits that may be realized in numerous applications. Many of theearlier patents referenced in this application fall under this class ofabrasive surfaces.

Despite numerous advancements in the field of abrasives there is a needfor discontinuous abrasive particle releasing surfaces for wet sanding,grinding, and polishing operations.

It is an object of this invention to provide wet low speed sanding,grinding and polishing surfaces.

It is a further object of this invention to provide numerous grades ofwet sanding, grinding, and polishing surfaces.

It is a further object of this invention to provide wet sanding,grinding, and polishing surfaces resistant to excess build up of debris

It is a further object of this invention to provide wet sanding,grinding, and polishing surfaces in both rigid and flexible forms.

It is a further object of this invention to provide wet sanding,grinding, and polishing surfaces that are low in cost.

It is a further object of this invention to provide simple methods forproducing wet sanding, grinding, and polishing surfaces.

Finally it is an object of this invention to provide wet sanding,grinding, and polishing surfaces that may be used for extended periodsof time without wearing out.

SUMMARY OF THE INVENTION

This invention therefore proposes discontinuous abrasive surfacesemploying discrete areas containing abrasive particles that arecontinuously released in free form during wet low speed sanding,grinding, and polishing operations. The discontinuous abrasive surfacesof the present invention may consist of abrasive containing protrusionsattached to rigid or flexible surfaces or alternatively may be comprisedof closed cell foam compositions impregnated with abrasive materialssuch as aluminum oxide. The voids present in the discontinuous abrasivesurfaces serve to hold water and remove debris.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a lapping surface suitable for grinding surfaces flat.

FIG. 2 shows a blank grinding block having an adhesive zone for mountingdisposable lapping surfaces.

FIG. 3 shows a lapping block consisting of a lapping surface adhered tothe top of a flat surfaced block.

FIG. 4 shows a cross sectional view of numerous surface protrusionsembedded with hard abrasive particles.

FIG. 5 shows a cross sectional view of numerous flat topped surfaceprotrusions embedded with hard abrasive particles.

FIG. 6 shows a sectional view of a low speed sanding disc for a rotarytool.

FIG. 7 shows a hand held abrasive foam sanding block of the presentinvention.

FIG. 8 shows a hand held abrasive article made entirely out of the foambased abrasive of the present invention.

FIG. 9 shows a sectional view of a low speed wet abrasive foam disc foruse with a rotary tool.

FIG. 10 shows an abrasive fabric employing polymeric resin protrusionsof the present invention embedded with coarse aluminum oxide.

FIG. 11 shows an abrasive loaded polymeric resin protrusion having a topsurface portion containing a pattern of grooves and ridges.

FIG. 12 shows an abrasive fabric glove having numerous abrasiveprotrusions attached to working surfaces in accordance with the presentinvention.

FIG. 13 shows a sectional view of a low speed wet sanding disc for arotary tool having a plurality of layers of surface protrusionscomprised of hard abrasive particles dispersed within a softer materialmatrix.

FIG. 14 shows a sectional view of cloth material for low speed wetsanding having a plurality of layers of surface protrusions comprised ofabrasive particles dispersed within a softer material matrix.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a lapping surface suitable for grinding surfaces flat.Lapping surface 2 is comprised of numerous protrusions 4 extendingupward from rigid backing laminate 6. Protrusions 4 may take the form ofnumerous shapes including polygons such as squares and hexagons,spheres, such as those shown in FIG. 4, and/or modified spheres such asthose shown in FIG. 5. Furthermore, the top surfaces of protrusions 4may have added grooves as shown in FIG. 9. It should be noted thatprotrusions 4 are separated from each other and therefore may beconsidered to be discontinuous. The spaces formed between individualprotrusions 4 provide means for holding water and for the rapid removalof debris. Protrusions 4 may be comprised of a relatively soft matrixmaterial such as a polymer impregnated with abrasive particlespossessing a degree of hardness significantly greater than that of thematrix material itself. The result is an abrasive particle releasingsurface for low speed wet lapping operations providing good abrasiveproperties. It should be noted that it may be desirable to control thehardness of the protrusions themselves. Opposite first major surface 2of rigid backing laminate 6 is a second major surface (not shown) thissecond major surface may have mounting hardware and/or materials such aspressure sensitive adhesives to facilitate mounting to a more rigid flatsubstrate surface.

Polymeric resin based materials such as epoxy may be cast in a suitablemold. For example, a laminate construction may be assembled havingnumerous protruding spherically shaped particles. The laminate may thenbe treated with a suitable release coating and used to make a siliconerubber mold. Once the mold is cured, the laminate may then be removed.The now vacant mold may then be used to cast a lapping surface. Abrasivepowder may be first sprinkled evenly in the numerous voids in the moldthat are to become protrusions. Abrasive loaded polymeric resin such asepoxy may then be added on top of the already existing free abrasiveparticles residing within the individual discrete protrusion cavitieswithin the mold. If desired, further addition of abrasive particles tothe epoxy resin in the mold may then be carried out followed by allowingthe above described composition to set into a hard mass.

West system 105 epoxy resin (West Systems Inc. PO Box 665 Bay City,Mich. 48707 USA) has been used for producing working prototypesemploying aluminum oxide abrasive. It should be noted that aluminumoxide is a dense material and therefore tends toward settling to thebottom of the mold. Since the bottom of the mold represents the tops ofthe protrusions in the final part, this method of manufacture may beemployed to keep numerous abrasive particles on the outer exposedsurfaces of the protrusions themselves. This particular configurationmay help to facilitate the initial release of abrasive particles. Thistechnique may be employed to improve the initial release of abrasiveparticles on first time use. Once the process of abrasive particlerelease starts, it becomes self sustaining.

FIG. 2 shows a blank grinding block having an adhesive zone for mountingdisposable lapping surfaces. Block 8 is shown having adhesive pattern 10on top surface 12. Top surface 12 of block 8 is flat and therefore helpsto maintain flatness of the final assembly.

FIG. 3 shows a lapping block 14 consisting of top exposed abrasiveparticle lapping surface portion 20 (lapping surface 2 of FIG. 1)attached to top flat surface portion 18 of base block portion 16.Exposed abrasive particle releasing lapping surface portion 20 is shownto be larger in area than side surface portion 16 and therefore may beconsidered a first major surface of lapping block 14. Lapping block 14has a second major surface (not shown) oppositely facing first majorsurface 20. Lapping block 14 is shown having side surface portion 16 andtop flat surface portion 18. Also shown is disposable lapping pad 20attached to top surface 18 of block 16.

Lapping block 14 is suitable for lapping small articles flat. Thearticle may be glued to a holder and lapped in a circular motion byhand, or alternatively lapped at a relatively slow rate by machine. Somearticles may also be held directly by hand and subsequently lapped flat.In many instances water in pure form or with special additives may beemployed in the process. Generally speaking the lapping surfaces of thisinvention will retain water in the voids between surface protrusions.Employing water as a lubricant may also help to flush debris from thearea being used. When finished, the lapping surface may be cleaned ofresidual debris with running water. When the lapping surface portion 20of lapping block 14 becomes worn out, it can be replaced at a reasonablecost. Removable attachment means such as pressure sensitive adhesivesmay be employed to achieve this end.

FIG. 4 shows a cross sectional view of numerous surface protrusionsshown in discontinuous arrangement comprised of abrasive particlesdispersed within a softer material matrix such as epoxy resin. Laminatebacking portion 22 is shown along with attached protrusions 24. Attachedprotrusions 24 are shown having abrasive particles 25 embedded intosofter material matrix portion 27.

FIG. 5 shows a cross sectional view of numerous protrusions having aflat top surface geometry shown in discontinuous arrangement comprisedof abrasive particles dispersed within a softer material matrix such asepoxy resin. Laminate backing portion 26 is shown along with attachedprotrusions 28. Attached protrusions 28 are shown having abrasiveparticles 29 embedded into softer material matrix portion 31.

FIG. 6 shows a sectional view of a low speed sanding disc for a rotarytool. Abrasive particle releasing disc 33 is shown having abrasivereleasing first major top surface portion 37 along with rigid backingportion 35 and central hole 39 for mounting to a shaft (not shown). Topabrasive releasing surface portion 37 is comprised of numerousprotrusions 41 fixedly attached to rigid backing portion 35. Protrusions41 are comprised of hard abrasive particles dispersed within a softermaterial matrix. Protrusions 41 are shown in greater detail in FIGS. 4and 5. Bottom surface portion 47 of rigid backing portion 35 may beregarded as a second major surface portion.

Abrasive particle releasing disc 33 is suitable for wet rotary sandingoperations. A shaft may be attached using central hole 39 and a threadedscrew. The shaft may be subsequently fitted into the chuck of a lowspeed rotary tool such as a drill. A relatively low speed of about 50 to500 RPM may be employed to wet sand numerous surfaces. It should benoted that high RPM conditions of 1000 or more may result in excess lossof water employed in wet sanding operations.

FIG. 7 shows a hand held abrasive foam sanding block of the presentinvention for wet low speed sanding, grinding, and polishing operations.Abrasive foam block 30 is shown having side portion 32 along withexposed abrasive particle releasing surface portion 34. Side portion 32has a thin skin over the surface as a result of the molding process usedto prepare adhesive foam block 30. Exposed abrasive particle releasingsurface portion 34 is shown having closed foam cells 36 that have beensevered by a sharp knife (not shown) and are therefore exposed. Exposedclosed foam cells 36 are made of a rigid material such as polyurethanein order to maintain a rigid geometry during use and form adiscontinuous surface for holding water and removing debris during wetsanding, grinding, and polishing operations. The closed cell foammaterial of exposed abrasive particle releasing surface portion 34 isshown to be larger in area than side surface portion 32 and thereforemay be considered a first major surface of abrasive foam block 30. Asecond major surface (not shown) is on the opposite side from exposedparticle releasing surface portion 34 of abrasive foam block 30.

FIG. 8 shows a hand held abrasive article made entirely out of thediscontinuous rigid closed cell foam based abrasive material of FIG. 7.Hand held abrasive article 38 is shown having bottom portion 40 alongwith handle portion 42. Also shown are handle mounts 44 used to attachhandle portion 42 to bottom portion 40. It should be noted that handheld abrasive article 38 may be one continuous piece consisting ofabrasive foam material that has been formed in a single operation in asuitable mold (not shown). Exposed discontinuous hard abrasive particlereleasing surface 49 of hand held abrasive article 38 forms a firstmajor surface and may be used for wet sanding, grinding, and polishingoperations. Second major surface 51 is shown opposite of first majorsurface 49. Second major surface 43 serves as the attachment surface forhandle 42 using handle mounts 44.

The abrasive foam compositions of the present invention are intended forlow speed wet mechanical as well as wet hand sanding, grinding, andpolishing operations. In general, no reinforcement is needed and thecompositions may be adjusted to attain desirable levels of rigidity,strength, and rate of wear. Furthermore, the addition of excess abrasivematerials to the polymeric foam compositions of the present inventionmay result in rapid wear degradation of the foam and associated rapidrelease of abrasive particles. These abrasive particles may then findtheir way into crevices thereby enhancing sanding, grinding andpolishing operations. In order to achieve this end, the abrasivematerials may each have a percent composition in the mix that has theabove described unique desirable properties. Outlined below are severalexamples of the abrasive loaded polyurethane closed cell foamcompositions of the present invention.

EXAMPLE 1

5.0 grams of foam A polyurethane foam pre-polymer from Plastic Depot(2900 San Fernando Blvd Burbank, Calif. 91054) were placed into a smallplastic cup. To this were added 5.0 grams of 70 grit aluminum oxideabrasive. The mixture was then stirred with a wooden popsicle stickuntil uniform. In a separate plastic cup were placed 5.0 grams of foam Bpolyurethane pre-polymer from the same source as the foam A. To thiswere added 5.0 grams of 70 grit aluminum oxide abrasive and the mixturestirred until uniform. Then two mixtures were then combined and stirreduntil uniform. The resultant mixture was then poured into a smallpolyethylene container and allowed to foam and subsequently cure. Thecured foam composition was then allowed to sit overnight to stabilize.The foam abrasive composition was then removed from the polyethylenecontainer. A small section of the outside portion was cut off with asharp knife to expose the foam cells underneath the outside skin. Asmall amount of water was placed on this exposed surface. This wetexposed surface was then used to sand the paint off of a soda can.Removal of the thin paint layer occurred within a few seconds leaving ascratched surface behind. It should be noted that the aluminum surfaceunderneath the paint did not bind up as often happens with sand paperbut rather tended to disperse in the water and accumulate in the exposedvoids of the foam.

EXAMPLE 2

The experiment of example 1 was repeated with increasing concentrationsof 70 grit aluminum oxide abrasive. At a concentration of 70% by weight,the foam composition became exceedingly weak and readily broke off whenwet sanding rough surfaces. The resulting particles formed a mixture ofbroken off foam and free aluminum oxide abrasive. This particularmixture was exceedingly efficient at sanding rough and irregularsurfaces.

EXAMPLE 3

The experiment of example 2 was then repeated with 100 grit aluminumoxide abrasive. It was found that a concentration of aluminum oxide of66% was required to attain similar results.

EXAMPLE 4

The experiment of example 3 was repeated with finely divided aluminumoxide polishing powder. It was found that a concentration of this finelydivided aluminum oxide of about 50% by weight was required to disruptthe polyurethane foam to a level sufficient to cause its break up duringuse. The resulting use of this composition produced good polishingproperties to rough wet surfaces.

EXAMPLE 5

5.0 grams of foam A polyurethane foam pre-polymer from Plastic Depot(2900 San Fernando Blvd Burbank, Calif. 91054) were placed into a smallplastic cup. To this were added 8.0 grams of finely divided ferric oxideabrasive. The mixture was then stirred with a wooden popsicle stickuntil uniform. In a separate plastic cup were placed 5.0 grams of foam Bpolyurethane pre-polymer from the same source as the foam A. To thiswere added 8.0 grams of finely divided ferric oxide abrasive and themixture stirred until uniform. The two mixtures were then combined andstirred until uniform. The resultant mixture was then poured into asmall polyethylene container and allowed to foam and subsequently cure.The cured foam composition was then allowed to sit overnight tostabilize. The foam abrasive composition was then removed from thepolyethylene container. A small section of the outside portion was cutoff with a sharp knife to expose the foam cells underneath the outsideskin. A small amount of water was placed on this exposed surface. Thiswet exposed surface was then used to polish rough sanded automotivepaint. Polishing was quick with noticeable results occurring within afew seconds leaving a polished surface behind. It should be noted thatthe resulting debris tended to disperse in the water and accumulate inthe exposed voids of the foam.

FIG. 9 shows a sectional view of a low speed wet abrasive foam disc foruse with a rotary tool. Abrasive particle releasing foam disc 53 isshown having abrasive releasing first major top surface portion 55 alongwith rigid backing portion 57 and central hole 59 for mounting to ashaft (not shown). Top abrasive releasing surface portion 55 iscomprised of numerous abrasive particles embedded into closed cell foamattached to rigid backing portion 57. Bottom surface portion 61 of rigidbacking portion 57 may be regarded as a second major surface portion.

Abrasive particle releasing disc 53 is suitable for wet rotary sandingoperations. A shaft may be attached using central hole 59 and a threadedscrew. The shaft may be subsequently fitted into the chuck of a lowspeed rotary tool such as a drill. A relatively low speed of about 50 to500 RPM may be employed to wet sand numerous surfaces. It should benoted that high RPM conditions of 1000 or more may result in excess lossof water employed in wet sanding operations.

FIG. 10 shows an abrasive fabric 46. Abrasive fabric 46 is comprised ofa flexible water absorbent fabric backing layer 48 along with attachedabrasive loaded polymeric resin protrusions 50. Abrasive fabric 46 isshown as a discontinuous surface that releases hard abrasive particlesduring low speed wet sanding, grinding, and polishing operations. Theseparation of individual abrasive loaded polymeric resin protrusions 50between each other forms a discontinuous surface. Also shown is materialmatrix portion 52 in the form of a polymer resin such as epoxy embeddedwith coarse aluminum oxide abrasive 54 having a hardness significantlygreater than polymer matrix portion 52. Abrasive fabric 46 may be usedfor machine driven sanding surfaces such as belts and discs as well ashand sanding applications.

It should be noted that the protrusions themselves provide points ofhigh pressure that facilitate wet sanding and grinding operations. Itshould also be noted that water absorbent flexible fabric 48 employedallows individual abrasive loaded polymeric resin protrusions to followsurface contours during wet sanding operations in addition to absorbingand releasing excess water during these same operations. This may beused to significantly control the moisture of surfaces during wetsanding operations. Individual protrusions 54 may have grooves likethose shown in FIG. 11.

FIG. 11 shows an abrasive loaded polymeric resin protrusion 56 having atop surface portion 58 containing a pattern of grooves 60. Grooves 60provide means for holding water and for the subsequent removal of debrisin wet low speed sanding, grinding, and polishing operations.Furthermore, ridges 62 resulting from grooves 60 in top surface portion58 provide for increased pressure at the start of wet sandingoperations. This added pressure helps to facilitate the process ofdislodging abrasive particles 62 and assures a good start to the wetsanding process. Once ridges 64 wear, abrasive particles 62 willcontinue to be released during use.

The above described abrasive loaded polymeric resin protrusions of FIG.9 were prepared in the following manner. A mold pre-form was made in thefollowing manner. A 4″×6″ piece of flat glass was thoroughly cleaned anddried. To this surface were attached Vitreous Glass Mosaic Tiles(Landscape L8⅜″-⅙ LB from Mosaic Mercantile). The tiles were evenlyspaced in eleven rows of seven having their widest side facing downagainst the glass surface. Two part five minute epoxy resin was thenused to firmly attach the tiles to the glass surface. It should be notedthat the tiles themselves were 0.4″ square at the bottom tapered evenlyto 0.325″ square at the top, and had an overall thickness of 0.15″. Thetop surface had three ridges as shown in FIG. 9. Once hard, the epoxywas allowed to further cure overnight. A thin layer of vegetable oil wasapplied to the entire tile coated glass surface and the glass placedsmooth side down in a 5″×7″ polyethylene flat bottom container. Onehundred and fifty grams of two part silicone RTV rubber molding compound(PD-1000-A) from Plastic Depot 2907 San Fernando BLVD Burbank, Calif.91504 Tel# 818-843-3030) were mixed thoroughly in accordance with theenclosed instructions and carefully poured over the mold pre-form in thepolyethylene container. The silicone rubber was allowed to cure at roomtemperature for twenty four hours. The mold was then removed from thepolyethylene container and peeled off from its pre-form. The siliconemold was then thoroughly washed with a strong detergent to removeresidual vegetable oil and subsequently allowed to dry.

Fifteen grams of West systems 105 epoxy resin were mixed with 3.0 gramsof West systems 205 fast curing catalyst. The mixture was stirredthoroughly followed by the addition of 36 grams of 70 grit coarsealuminum oxide abrasive. The mixture was then stirred until completelyuniform. Immediately after mixing the resultant abrasive paste wasplaced into the voids in the silicone mold. A flat edge was then draggedagainst the mold surface to level the resin mixture in the voids. Theresin was allowed to cure for twenty four hours. Once cured, theabrasive protrusions were removed from the mold and inspected forquality. The best sixty samples were then ground flat on their largestside and attached to the front surface of a cotton glove using Westsystems 105 epoxy resin and 205 hardener. Unfortunately, the glovetended to absorb the low viscosity resin. The abrasive protrusions werethen removed and wiped clean with a paper towel. The glove with thestill wet adhesive was then stuffed with paper towels to prevent theresin from gluing the glove shut. The resin was allowed to hardensomewhat. The paper towels in the glove were then removed and the resinon the glove allowed to thoroughly cure. Five minute epoxy was thenapplied to the widest side of each abrasive protrusion and theprotrusions glued to the glove at the positions corresponding to thepreviously cured spots of resin on the glove. This approach workedexceptionally well with the resultant glove having sixty abrasiveprotrusions firmly attached to the required areas for hand sandingoperations.

The above described glove was then tested against numerous surfacesincluding automotive paint on plastic, automotive paint on metal,aluminum, painted aluminum, and glass. This testing was carried out withand without water. The dry sanding produced numerous coarse scratches inthe above mentioned surfaces while the wet sanding was more rapid andcomplete with more uniform finer sanding. It should be noted that thisparticular sanding glove rapidly wet sanded all of the above describedsurfaces by hand in a matter of seconds.

FIG. 12 shows an abrasive fabric glove having numerous discrete abrasiveprotrusions attached to major working surfaces in accordance with thepresent invention. Sanding glove 62 is shown having abrasive loadedpolymeric resin protrusions 64 that are discontinuous from each otherand attached to glove 66 with epoxy resin 68. Also shown are ridges 70on protrusions 64. Ridges 70 on protrusions 64 provide points of highpressure and help to hold water during the first use. Protrusions 64consist of polymeric resin portion 72 along with abrasive particleportion 74 thereby forming a mixture of hard abrasive particlesdispersed within a softer epoxy resin material matrix.

FIG. 13 shows a sectional view of a low speed wet sanding disc for arotary tool having a plurality of layers of surface protrusionscomprised of hard abrasive particles dispersed within a softer materialmatrix. Abrasive particle releasing disc 76 is shown having abrasivereleasing first major top surface portion 78 along with rigid backingportion 80 and central hole 82 for mounting to a shaft (not shown). Topabrasive releasing surface portion 78 is comprised of numerousprotrusions 82 fixedly attached to rigid backing portion 80 forming afirst layer 84. A second layer 86 of protrusions 88 are also shown.Protrusions 88 forming second layer 86 are shown fixedly attached toprotrusions 82 of first layer 84. Protrusions 82 and 88 are comprised ofhard abrasive particles dispersed within a softer material matrix.Protrusions 82 and 88 are shown in greater detail in FIGS. 4 and 5.Bottom surface portion 90 of rigid backing portion 80 may be regarded asa second major surface portion.

FIG. 14 shows a sectional view of fabric material for low speed wetsanding and grinding having a plurality of layers of surface protrusionscomprised of abrasive particles dispersed within a softer materialmatrix. Abrasive particle releasing fabric 92 is shown having abrasivereleasing first major top surface portion 94 along with flexible waterabsorbent fabric portion 96. Top abrasive releasing surface portion 94is comprised of numerous protrusions 98 fixedly attached to flexiblewater absorbent fabric portion 96 forming a first layer 100. A secondlayer 102 of protrusions 104 are also shown. Protrusions 104 formingsecond layer 102 are shown fixedly attached to protrusions 98 of firstlayer 100. Protrusions 98 and 104 are comprised of hard abrasiveparticles dispersed within a softer material matrix. Protrusions 98 and104 are shown in greater detail in FIGS. 4 and 5. Bottom surface portion106 of flexible water absorbent fabric portion 96 may be regarded as asecond major surface portion.

The above descriptions of FIGS. 13 and 14 outline a plurality of layers.These may be formed by forming a first layer of abrasive containingprotrusions followed by adhesion of a second layer on top of the firstlayer using a suitable adhesive material such as epoxy.

Those skilled in the art will understand that the preceding exemplaryembodiments of the present invention provide foundation for numerousalternatives and modifications. These other modifications are alsowithin the scope of the limiting technology of the present invention.Accordingly, the present invention is not limited to that preciselyshown and described herein but only to that outlined in the appendedclaims.

Drawings

1. A discontinuous abrasive particle releasing surface for low speed wetsanding, grinding, and polishing operations comprising: a rigid backinghaving a first major surface and a second major surface; a plurality ofabrasive particle releasing protrusions fixedly attached to said rigidbacking to at least one said major surface; whereby said plurality ofparticle releasing protrusions are comprised of abrasive particlesdispersed within a softer material matrix.
 2. A discontinuous abrasiveparticle releasing surface for low speed wet sanding, grinding, andpolishing operations as recited in claim 1, wherein said discontinuousabrasive particle releasing surface is removably attached to a secondsurface.
 3. A discontinuous abrasive particle releasing surface for lowspeed wet sanding, grinding, and polishing operations as recited inclaim 1, wherein said discontinuous abrasive particle releasing surfaceis a lapping surface.
 4. A discontinuous abrasive particle releasingsurface for low speed wet sanding, grinding, and polishing operations asrecited in claim 1, wherein said plurality of protrusions have a flattop surface geometry.
 5. A discontinuous abrasive particle releasingsurface for low speed wet sanding, grinding, and polishing operations asrecited in claim 1, wherein said soft matrix material is a polymer.
 6. Adiscontinuous hard abrasive particle releasing surface for wet low speedsanding, grinding, and polishing operations comprising: a rigidpolymeric closed cell foam substrate having at least one major surface;said at least one major surface of said rigid polymeric closed cell foamsubstrate having exposed voids along with a plurality of abrasiveparticles dispersed within said foam; whereby said plurality of abrasiveparticles are continuously released in free form during said wetsanding, grinding, and polishing operations.
 7. A discontinuous hardabrasive particle releasing surface for wet low speed sanding, grinding,and polishing operations as recited in claim 6 wherein a handle is madeentirely of the discontinuous abrasive foam material.
 8. A discontinuoushard abrasive particle releasing surface for low speed wet sanding,grinding, and polishing operations comprising: a flexible backing havinga first major surface and a second major surface; a plurality ofprotrusions fixedly attached to at least one of said major surfaces;whereby said plurality of protrusions are comprised of abrasiveparticles dispersed within a softer material matrix.
 9. A discontinuoushard abrasive particle releasing surface for low speed wet sanding,grinding, and polishing operations as recited in claim 8, wherein theflexible backing is fabric.
 10. A discontinuous hard abrasive particlereleasing surface for low speed wet sanding, grinding, and polishingoperations as recited in claim 9, wherein the fabric is formed into aglove.
 11. A discontinuous hard abrasive particle releasing surface forlow speed wet sanding, grinding, and polishing operations as recited inclaim 8 wherein the soft material matrix is a polymer.
 12. Adiscontinuous hard abrasive particle releasing surface for low speed wetsanding, grinding, and polishing operations as recited in claim 8wherein the protrusions have a top surface containing a pattern ofgroves for holding water and removing debris and ridges for increasingthe pressure at the start of wet sanding, grinding and polishing.
 13. Adiscontinuous abrasive particle releasing surface for low speed wetsanding, grinding, and polishing operations as recited in claim 1,wherein said abrasive particle releasing protrusions are formed into aplurality of layers.
 14. A discontinuous hard abrasive particlereleasing surface for low speed wet sanding, grinding, and polishingoperations as recited in claim 8 wherein said plurality of protrusionsare formed into a plurality of layers.